/*
 * Copyright (C) 2017-2019 Hazuki
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package jp.hazuki.yuzubrowser.ui.widget.recycler

import androidx.recyclerview.widget.RecyclerView

abstract class LoadMoreListener(private val linearLayoutManager: androidx.recyclerview.widget.LinearLayoutManager) : RecyclerView.OnScrollListener() {

    private var previousTotal = 0
    private var loading = true
    private var currentPage = 1

    override fun onScrolled(recyclerView: androidx.recyclerview.widget.RecyclerView, dx: Int, dy: Int) {
        super.onScrolled(recyclerView, dx, dy)

        if (dx == 0 && dy == 0) return

        val totalItemCount = linearLayoutManager.itemCount
        val lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition()

        if (loading) {
            if (totalItemCount > previousTotal) {
                loading = false
                previousTotal = totalItemCount
            }
        }

        if (!loading && lastVisibleItem >= totalItemCount - 10) {
            currentPage++

            onLoadMore(currentPage)

            loading = true
        }
    }

    abstract fun onLoadMore(current_page: Int)
}
